This invention relates generally to recloseable bags of the type typically fabricated from plastic film and which comprises two opposing bag walls which are sealed together at the side edges and the bottom, and is particularly concerned with a new and improved recloseable, separable, flexible plastic fastener profile assembly for such bags which will efficiently resist opening due to forces which develop inside the bag, particularly when filled with product.
Recloseable bags have attained widespread use for containing various products, with convenient access thereto provided by recloseable fastener profile assemblies. However, a number of problems exist with respect to this type of closure mechanism.
When the fastener profile assemblies are manufactured separately and sealed onto the film during fabrication of the bag, there exists the problem of correct alignment of the seals with respect to the profile assemblies. The preferred embodiment is when the seal location is at the top of the profile assemblies toward the opening of the bag. This allows for easy opening from the top of the bag and discourages unintentional opening due to internal pressures on the bag walls. However, it is difficult to consistently seal the profile assemblies in the correct location. Consequently, it is desirable that a method and means be provided to effect such consistent sealing.
Another problem that has long been recognized in regard to flexible fastener profile assemblies is the unintentional opening of bags caused by internal pressures on the bag walls due to the load of contents or trapped air inside the bag. While many attempts have been made to alleviate this problem, none have been completely satisfactory. Representative are U.S. Pat. Nos. 3,338,284, 3,372,442 and 3,633,642. Manufacturing problems such as a more difficult extrusion process, a decreased production rate and associated therewith a higher production cost, are associated with the methods represented in the above enumerated patents.
Additional attempts have been made to alleviate this problem in U.S. Pat. Nos. 2,780,261 and 3,054,434. These patents illustrate a single hinge arrangement on one side of the flexible fastener profile assembly. This arrangement addresses the problem of the bag opening unintentionally from inside forces, however, this arrangement at the same time causes intentional opening of the bag to be more difficult. In particular, U.S. Pat. No. 3,054,434 illustrates a slide bar to assist in the interconnecting and unconnecting of the fastener profile assembly. This slide bar requires additional assembly and additional cost. Opening of the bags without such a slide bar is awkward and troublesome due to the unbalanced upper portion of the fastener profile assembly; there being a hinge arrangement on only one side of the fastener profile. U.S. Pat. No. 2,780,261 illustrates a sliderless fastener profile assemby, but is equally awkward and unbalanced.